Board: ROCK Pi 4 Plus V1.73 (Wi-Fi + PoE header, onboard eMMC). The unit came from a Jeedom Pro box that had stopped working before I touched it.
What works: maskrom entry (SPI disabled by shorting pins 23/25, USB A-A cable, Maskrom entry also happens on its own without the button). rid returns 45 4D 4D 43 20. TestDevice succeeds in RKDevTool 2.96.
What fails: rfi / ReadFlashInfo reports Samsung, 30 MB, 62688 sectors (0xF4E0) with loaders v1.27.126, v1.20.119 and spinor v1.15.114, on macOS (rkdeveloptool 1.32) and Windows (RKDevTool 2.96). Writing a marker at LBA 1000 and reading it back does not match. ReadCapability shows SwitchStorage: Disable; RKDevTool says “Failed to switch storage” when the target is EMMC. Writing a 64 MB zero.img “completes” at 100%, but read-back shows a fill pattern beyond 32 MB.
Is this a dead eMMC, or is there a known recovery procedure (specific loader, button/pin, other)?